Abstract: Ultra short radius horizontal radial drilling is a novel oil drilling and exploitation technology.During drilling operation,when drill pipe passthrough whipstock rollerpass,the varying curvature radius of drill pipe cause the bending drill pipe behaves plastic state.Deformation of the pipe cross section and the relevant drag force from the whipstock pass highly affect horizontal advan cing capability of the drill pipe.This paper,the ideal rigid plastic analysis based on the stress strain relation of the pipe is presented the equations of the long axis and short axis extreme values of the elliptically deformed pipe cross section,and of the bending whipstock resistance exerting on advancing drill pipe.The effects of the roller pass friction and the reverse force of water jet on the pipe advancing resistance are analyzed.The equation in this paper are verified by experiments under various conditions,and they are of practical importance in designing whipstock selecting pipe material and optimizing parameter.

Key words: ultra short radius horizontal radial drilling, whipstock, cross-section of drill pipe, stress, analysis plastic deformation, axial stress

摘要： 径向水平钻井技术是开发油田的一种新技术,钻杆在经过斜向器时曲率半径反复变化,钻杆处于应力-塑性应变状态.钻杆截面变形量大小及斜向器弯道阻力的大小对能否正常钻进至关重要.分析了钻杆截面的应力-应变关系,在假定钻杆为理想刚塑性材料的条件下,推导出了钻杆截面的长、短轴极限变形量及钻杆转弯时的阻力计算公式,分析了滑道摩擦系数、射流反力对阻力的影响,从三种条件下公式的计算结果与实验对比中可证明这些公式的正确性,对斜向器的设计和钻杆的选材以及确定实际钻进的工作参数具有指导意义.

关键词: 径向水平井, 斜向器, 钻杆截面, 受力分析, 塑性变形, 轴向应力